Brian Truitt, USA TODAY8:57 a.m. EDT July 19, 2013

Asa Butterfield and Hailee Steinfeld brave wires and harnesses for sci-fi movie adaptation.

SAN DIEGO — Hailee Steinfeld garnered an Oscar nomination for her work in the remade WesternTrue Grit, but she’s off to a whole new frontier inEnder’s Game.

The upcoming adaptation of Orson Scott Card’s classic 1985 sci-fi novel stars Steinfeld as well as fellow 16-year-old Asa Butterfield, who plays Ender Wiggin, a gifted kid sent to a galactic military academy to prepare for an alien invasion.

The fact that Ender’s Game (in theaters Nov. 1) is at Comic-Con this week is no surprise — it even has a huge Ender’s Game Experience attraction parked in front of the San Diego Convention Center. But as the book itself is starting to become part of required-reading lists for kids, it’s another example sci-fi’s importance in culture.

“People are starting to really respond to it,” says the London-born Butterfield. “Ender’s Game as a book, it’s more than a science-fiction. There’s a lot to it, which is what made it so popular and one of the reasons why we’re so excited about sharing it.”

MORE: Complete coverage of Comic-Con 2013

Aside from the fact that the characters have been made older, the actor feels that the movie, directed by Gavin Hood and co-starring Harrison Ford and Ben Kinglsey, is as true to the book as a film can be.

That kind of authenticity also meant a whole bunch of space scenes and, for Butterfield and Steinfeld, training for zero gravity.

The filmmakers used rigs to hoist the actors and make them feel as if they were in space. “If you’re scared of heights, you just had to get over it,” Butterfield says. “There’s nothing you can do about it. We all had a great time up there.”

Steinfeld recalls about three months spent on wires “floating around, flipping around, being thrown into pads.”

“And shooting people,” Butterfield says.

“The list goes on,” says Steinfeld, who plays Petra Arkanian, Ender’s friend at Battle School. “I don’t really think we had time to worry about it.”

Does it help to be young when doing all that stuff? “I would assume so,” Butterfield deadpans with a smile.

“I guess we don’t really know any different,” Steinfeld says. “It is very uncomfortable and hard at first, to say the least.”

All that wire work meant the use of tight harnesses to keep them from falling, on top of wearing skintight material akin to a neoprene wetsuit that was covered in pads and rubber. “It was like a sauna,” Butterfield says.

Because of the sound, filmmakers couldn’t run air conditioning to keep them cool, says Steinfeld, though Butterfield notes that they did have fans in their 8-pound helmets, “which kept it from fogging up.”

All that made the teens and their fellow sci-fi youngsters feel much more immersed in the world of Ender’s Game.

“We’re sitting here talking about how uncomfortable it was, but the situation you’re in is uncomfortable and it works and you’re able to use that and take advantage of that,” Steinfeld says.

“I doubt they were comfortable 50 years in the future,” Butterfield figures.

“Yeah, I don’t know how we managed,” Steinfeld adds before giving him a high-five. “Maybe we’ll see. We’ll go to space in 50 years and see if the spacesuits are comfortable.”